lowering of metabolism after weight loss

A while ago there was some discussion on if the body adjusts metabolism
after weight loss to maintain the higher weight. Here's an article that
talks about the issue:

Why lost weight returns after dieting
http://www.news-medical.net/?id=2955

The data suggests that weight loss in obese, obesity-prone rats, induced
by caloric restriction, is accompanied by metabolic adaptations that
predispose one to regain the lost weight. In rats that are losing
weight, this is exhibited by a significant reduction in metabolic rate,
measured as both 24-hour energy expenditure and sleeping metabolic rate,
both independent of metabolic mass and energy intake. This adaptation
persists after eight weeks of intake-regulated weight maintenance, but
is no longer present with eight subsequent weeks of feeding at-will
where rats are regaining lost weight. While rats that are regaining
weight may have a shift in appetite that would contribute to their high
rate of weight regain, the drive to increase food intake remains the
most critical factor in the predisposition to regain lost weight. This
adjustment clearly weighs more on the energy balance equation than the
metabolic adjustment on energy expenditure observed in this or any other
study.

Additionally, the effect that energy intake, or more particularly,
carbohydrate intake, has on respiratory quotient [dividing the amount of
CO2 produced (VCO2) by the amount of oxygen uptake (VO2)]. RQ is much
more dramatic than the metabolic adjustment observed from weight
reduction. This drive to increase food intake likely involves
environmental stimuli (diet composition, food palatability, physical
activity) influencing motivational and metabolic components of a
genetically determined set of central systems.

While the data suggest that these metabolic adaptations might hinder
successful weight maintenance, it should not imply that successful
weight maintenance is unachievable. Even with the increased intake of
carbohydrates, regular physical exercise may be the key factor that
counteracts these metabolic adaptations to weight loss.

----

I notice that after everyone of these pronouncements saying how hard
weight is to lose they say something like it's not unachievable. How
hard does something have to be before people stop trying to achieve it?
Not very hard.

regular physical exercise may be the key factor that counteracts these
metabolic adaptations to weight loss.


for me its the only way to do it.

--
Tom
Exercise Today = Life Tomorrow

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----

I notice that after everyone of these pronouncements saying how hard
weight is to lose they say something like it's not unachievable. How hard
does something have to be before people stop trying to achieve it?
Not very hard.

Ignoramus21798 wrote:
It all depends on how much you want it.

So if you want it bad enough you can be a four minute miler? I think
not. Your physical body establishes what is ultimately possible.

Numerous people lose weight
and keep it off, not without difficulties. It is not impossible.

Nor is it easy enough to expect even the majority of people to be able
to do it.

Ignoramus21798 wrote:
On Thu, 14 Apr 2005 11:55:30 -0700, wendy wrote:

Ignoramus21798 wrote:

It all depends on how much you want it.

So if you want it bad enough you can be a four minute miler? I think
not. Your physical body establishes what is ultimately possible.


Any fat person can lose weight if they are calorie restricted (for
example, confined in a cage with limited food). It is unlike running.

That's not really the point though. What is important is how do you keep
the weight off when you are free in the wild.


Surely, we know that the majority of people cannot lose weight, and
the majority of those who can lose weight does not keep it off. So,
here, I agree with you.

I don't know about cannot, but it's a lot harder than people want to admit.

"wendy" wrote in message
...
Ignoramus21798 wrote:
On Thu, 14 Apr 2005 11:55:30 -0700, wendy wrote:

Ignoramus21798 wrote:

It all depends on how much you want it.

So if you want it bad enough you can be a four minute miler? I think
not. Your physical body establishes what is ultimately possible.


Any fat person can lose weight if they are calorie restricted (for
example, confined in a cage with limited food). It is unlike running.

That's not really the point though. What is important is how do you keep
the weight off when you are free in the wild.


Surely, we know that the majority of people cannot lose weight, and
the majority of those who can lose weight does not keep it off. So,
here, I agree with you.

I don't know about cannot, but it's a lot harder than people want to
admit.

Well...it's not rocket science either. Losing weight simply requires
consuming a few less calories per day than one burns.

That said, in today's world where calorie-dense food is ever present in
enormous quantities, and where most of us spend most of our days sitting on
our rear ends, it does require a degree of dedication to lose weight.

As with many other things in life, anything that requires patience and
persistence will tend to have a low rate of success. It's just a lot easier
for most people to reach for the bag of snacks and the remote control,
rather than get up off the couch and go for a walk. But, that's more an
issue of personal priorities than metabolism.

GG

"wendy" wrote in message
...

A while ago there was some discussion on if the body adjusts metabolism
after weight loss to maintain the higher weight. Here's an article that
talks about the issue:

Why lost weight returns after dieting
http://www.news-medical.net/?id=2955

The data suggests that weight loss in obese, obesity-prone rats, induced
by caloric restriction, is accompanied by metabolic adaptations that
predispose one to regain the lost weight. In rats that are losing
weight, this is exhibited by a significant reduction in metabolic rate,
measured as both 24-hour energy expenditure and sleeping metabolic rate,
both independent of metabolic mass and energy intake. This adaptation
persists after eight weeks of intake-regulated weight maintenance, but
is no longer present with eight subsequent weeks of feeding at-will
where rats are regaining lost weight. While rats that are regaining
weight may have a shift in appetite that would contribute to their high
rate of weight regain, the drive to increase food intake remains the
most critical factor in the predisposition to regain lost weight. This
adjustment clearly weighs more on the energy balance equation than the
metabolic adjustment on energy expenditure observed in this or any other
study.

Additionally, the effect that energy intake, or more particularly,
carbohydrate intake, has on respiratory quotient [dividing the amount of
CO2 produced (VCO2) by the amount of oxygen uptake (VO2)]. RQ is much
more dramatic than the metabolic adjustment observed from weight
reduction. This drive to increase food intake likely involves
environmental stimuli (diet composition, food palatability, physical
activity) influencing motivational and metabolic components of a
genetically determined set of central systems.

While the data suggest that these metabolic adaptations might hinder
successful weight maintenance, it should not imply that successful
weight maintenance is unachievable. Even with the increased intake of
carbohydrates, regular physical exercise may be the key factor that
counteracts these metabolic adaptations to weight loss.

----

I notice that after everyone of these pronouncements saying how hard
weight is to lose they say something like it's not unachievable. How
hard does something have to be before people stop trying to achieve it?
Not very hard.

That study reduced the rat's food intake rather drastically. Specifically,
"weight loss was induced by limiting calories to approximately 60 percent of
energy expenditure". This would be equivalent to a person who burns 2500
calories per day being limited to only 1500 calories per day.

There's also the issue of time frame. In the experiment, they took 16 weeks
to allow the rats to gain 10-15% body weight. But, they allowed only 2
weeks to reduce their body weight by that much.

It's possible the effect on metabolism seen in those rats was due to a
"starvation" response. If they had lost weight the weight slowly (the same
way they had gained it), it's possible the effect on metabolism would have
been different.

--
GG
http://www.WeightWare.com
Your Weight and Health Diary

Humans are not rats.

I recall a study that showed metabolism dropping by 15% when the fat on the
human body goes below a "setpoint." The setpoint was different for each
individual. 15% is not large enough to make weight management impossible.
However, it does tip the scales, so to speak.


"wendy" wrote in message
...

GaryG wrote:
Well...it's not rocket science either. Losing weight simply requires
consuming a few less calories per day than one burns.

And running a 4 minute mile simply require running a mile under 4 minutes.


As with many other things in life, anything that requires patience and
persistence will tend to have a low rate of success. It's just a lot easier
for most people to reach for the bag of snacks and the remote control,
rather than get up off the couch and go for a walk. But, that's more an
issue of personal priorities than metabolism.

Why is it easier? You don't forget to breath. You don't over drink
water. Why do you want to eat the snacks and use the remote control? It
could be different, but it's not. The influences are so built-in we
don't even recognize they are at play.

GaryG wrote:
It's possible the effect on metabolism seen in those rats was due to a
"starvation" response. If they had lost weight the weight slowly (the same
way they had gained it), it's possible the effect on metabolism would have
been different.


It's possible. But i believe that rate is about a 1 pound a month.

Cubit wrote:
Humans are not rats.

I recall a study that showed metabolism dropping by 15% when the fat on the
human body goes below a "setpoint." The setpoint was different for each
individual. 15% is not large enough to make weight management impossible.
However, it does tip the scales, so to speak.

A woman is not a man. One person is not the next. One race is not the
next. Like it or not animal models are what we learn a lot from. It
doesn't always work, but to dismiss any study based on animal models
isn't wise.

If i could guarantee you a 15% rate of return you would be a very happy
person.

As for weight management being impossible, that is not the argument. But
that's a pretty damn high standard.